Grinding wheel feeding mechanism



May 26, 1953 Filed Oct. 21, 1950 H. L. SWAINEY GRINDING WHEEL FEEDING MECHANISM fig] 2 Sheets-Sheet l rm/ nte HOMER L. SWA/ EY flccomey May 26, 1953 H. L. SWAINEY 2,639,563

- GRINDINGWHEEL FEEDING MECHANISM Filed Oct. 21, 1950 2 Sheets-Sheet 2 Anon/e7 Patented May 26, 1953 GRINDING WHEEL FEEDING MECHANISM Homer L. Swainey, Cleveland, Ohio, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application October 21, 1950, Serial No. 191,386

Claims. 1

The invention relates to grinding machines, and. more particularly to a grinding wheel feeding mechanism.

One object of the invention is to provide a simple and thoroughly practical feeding mechanism for precisely feeding a grinding wheel so as to control work size. Another object of the invention is to provide a feeding mechanism to feed the grinding wheel first at a grinding rate and then automatically to reduce the rate of ineed to a finishing feed prior to positively stopping the infeeding movement. Another object is to provide a feeding mechanism with an electric time delay relay for controlling the overall feeding movement so as to provide a predetermined grinding feed, a predetermined reduced finishing feed, a positive stop to limit the infeeding movement, and thereafter to control a period of dwell prior to withdrawal of the grinding wheel.

Another object is to provide a nut and screw feeding mechanism with an adjustable stop abutment and stop pawl to limit the infeeding movement of the grinding wheel in which the pawl is arranged to actuate a limit switch to change the grinding feed to a finishing feed before the infeeding movement is stopped. Other objects will be apparent from the foregoing disclosure.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. 1 is a combined hydraulic and electrical diagram of the feeding mechanism and the controls therefor;

Fig. 2 is a cross-sectional view through the grinding wheel feeding mechanism;

Fig. 3 is a fragmentary horizontal sectional view, on an enlarged scale, through the feeding mechanism clutch and the actuating mechanism therefor; and

4 is a fragmentary vertical section, on an enlarged scale, of the detent mechanism for holding the clutch either engaged or disengaged.

A grinding machine has been illustrated in the drawings comprising a base Ill which serves as a support for a transversely movable wheel slide l i. The wheel slide I I is supported on the usual V-way and flatway (not shown). The wheel slide II serves as a support for a rotatable wheel spindle I2 having a grinding wheel I3 mounted adjacent to one end thereof. The grinding wheel spindle I2 may be driven by any suitable source of power such as for example an electric motor (not shown) mounted on the wheel slide II.

The wheel slide I I is arranged to be fed transversely by means of a suitable feeding mechanism such as a rotatable feed screw I5 which is journalled in anti-friction bearings I6 and I1. A half-nut I8 depends from the under side of the wheel slide II and meshes with or engages the feed screw I5. A manually operable feed wheel I9 is mounted on the front of the machine base It. The feed wheel I9 is operatively connected to rotate a gear 20 which meshes with a gear 2I. The gear 2| is keyed on the forward end of a rotatable shaft 22. The rear end of the shaft 22 is slidably keyed within the forward end of a rotatable sleeve 23. The forward cylindrical end portion 24 of the feed screw I5 is slidably keyed within the hollow sleeve 23. The forward end of the portion 24 of the feed screw I5 is provided with a stop abutment 25 which is arranged to move into engagement with a rounded end of an adjustable stop screw 26 which is carried by the shaft 22.

In order to facilitate a rapid positioning movement of the grinding wheel, that is, rapidly moving the grinding wheel and its supporting slide to and from an operative position, a hydraulically operated mechanism is provided. The bearing H for the right-hand end of the feed screw I5 (Fig. 2) is supported by a slidably mounted sleeve 3!] which is connected to the forward end of a piston rod 3|. other end of the piston rod 3I and is slidably mounted within a cylinder 33. The piston rod 3 I, the piston 32 and the cylinder 33 are arranged in axial alignment with the feed screw I5.

A uitable feed control valve 35 is provided for controlling the admission and exhaust of fluid from the cylinder 33. The valve 35 is preferably a piston-type valve comprising a valve stem 36 having a plurality of valve pistons 31, 38 and 39 formed integrally therewith. A compression spring 40 serves normally to maintain the valve stem 36 in its right-hand end position, as illustrated in Fig. 1. A solenoid 4| is operatively connected to the right-hand end of the valve stem 36 and is arranged so that when energized, it serves to shift the valve stem 36 toward the left into a reverse position.

A suitable fluid pressure supply system is provided comprising a motor driven fluid pump 42 which draws fluid through a pipe 43 from a reservoir 44 and forces fluid under pressure to the A piston 32 is mounted on the 3 feed control valve 35. A pressure relief valve 46 is connected to the pipe 45 by means of which excess fluid under pressure may be bypassed directly through a pipe a! into the reservoir 44 so as to maintain a substantially uniform operating pressure in the hydraulic system.

In the position of the valve 35, as shown in Fig. 1, fluid under pressure passing through the pipe 45 enters a valve chamber 48 located between the valve pistons 37 and 38 and passes through a passage 49 into a cylinder chamber Bil to cause the piston 32 to move toward theright into the position illustrated in Fig. 1.' Movement'of the piston 32 toward the right also imparts a corresponding movement to the feed screw I5, the half-nut IS, the wheel slide I! so as to move the grinding wheel 13 to a rearward or inoperative position. During this movement of the piston 32 fluid within a cylinder chamber 51 may exhaust through a passage 52, through a valve chamber 53 located between the valve pistons 38 and 39 and pass out through an exhaust pipe 54 into the reservoir 44.

In. orderto slow down the rapid rearward movement of the piston 32, a dash pot mechanism is provided. The piston rod 3! is provided with a rearwardly extending stud 66 which is arranged when moved toward the right to engage a dash pot piston 6|. The dash pot piston BI is slidably mounted within a dash pot cylinder 62. When'the dash pot moves rearwardly, fluid is exhausted from the dash pot cylinder 52 through apipe=63 and through a throttle valve (54 and into the passage 52. A ball check valve 65 is provided so that fluid exhausting from the dash pot cylinder 62 must pass through the throttle valve 64. It will be readily apparent from the foregoing disclosure that until the stud 60 engages the dash pot piston El, the piston 32 will move at a rapid rate. After the stud 83 engages the dash pot, piston (ii the speed of movement of the piston is reduced to a predetermined slower rateas governed by fluid exhausting from the dashpot cylinder 62 through the pipe 63 and the throttle valve (34. It will be readily apparent from the foregoing disclosure that by adjustment ofthe throttle valve at, the rapid readward movement of the piston 32 may be reduced to a slower speed before the piston 32 engages the rear of the cylinder 33.

It is similarly desirable to provide a cushioning or slowing down movement of the piston 32 as it moves rapidly toward the left as the grinding wheel it approaches the workpiece to be ground. When the solenoid M is energized to shift the valve'stem 38 toward the right fluid under pressure from the pipe 45 is passed through the valve chamber 53 and through the passage 52 into the cylinder chamber 5| to cause the piston 32 to move rapidly toward the left (Fig. 1). Fluidunder pressure passing through the passage52 may also pass through the throttle valve Eli and the ball check valve 55, through the pipe 63 into the dash'pot cylinder 62 to return the dash pot piston El to its initial position. Theiniti'al rapid movement of thepiston 32 causes-fluid within the cylinder chamber 5!! to exhaust through a port 66, through the passage 49, through the valve chamber 48 and out through the exhaust pipe 5 5. When the valve piston 32 closes the port 66 just before the piston reaches the end of its stroke toward the left, that is when the stop abutment 25 engages the stop screw 25, fluid may then be exhausted through a passage It, and through a throttle valve-ll into the pas-- sage 49 thereby facilitating a reduction in speed of the forward movement of the piston 32 before the forward approaching movement cease A ball check valve 33 is connected between the port 6d and the passage GT which serves to facilitate a substantially unrestricted flow of fluid from the passage 49, through the port 69 into the cylinder chamber 50 so as to start the rapid rearward movement of the piston 32 when the solenoid il is deenergized.

A suitable cam operated feedin mechanism is provided for producing a slow precise feeding movement of the grinding wheel during the grinding operation. In the preferred form, a hydraulically operated mechanism is provided in which a fluid motor serves to produce a controlled rotary movement of the feed screw 15. As illustrated in the drawings a fluid pressure cylinder i5 is provided having a slidably mounted piston 76. The upper central portion of the piston l6 is-provided with rack teeth '51 meshing with a gear 78 which is keyed on a rotatable shaft '13. The shaft 19 is also provided with a gear is which meshes with the gear 2 i. It will be readily apparent from the foregoing disclosure that when the piston i8 is moved endwise within the cylinder l5, a rotary motion will be imparted to the feed screw l5 through the rack and gear mechanism above described.

A shuttle-type control valve Be is provided for controlling the admission to and exhaust of fluid from the cylinder 75. The valve 80 comprises a slidably mounted valve member having a plurality of spaced valve pistons 8|, E2 and 83 forming a pair of valve chambers 84 and 85. .A compression spring 36 is provided normally to hold the valve in a left-hand end position such as shown in Fig. 1. In order to shift the valve 80 into a right-hand end position, the pipe 45 is connected by a valve 87 with a pipe 88 which is in turn connected to a left-hand end chamber 89 within the valve 3%. When it is desired to shift the valve 86 into a right-hand end position, the valve 31 may be opened to admit fluidunder pressure from the pump 42 through the pipe 88 into the valve chamber 89.

In the position of valves 35 and 80 (Fig. 1) fluid under pressure entering the valve chamber 48 may pass through the pipe 99, through the valve chamber in the valve as, through a passage 9! into a cylinder chamber 92 to move the piston 16 toward the left into the position illustrated in Fig. 1. The left-hand movement of the piston 76 serves to impart a rotary motion to the feed screw l5 to cause a rearward movement of the nut I8, the wheel slide l l and the grinding wheel I3. During this movement of the piston 16 fluid within a cylinder chamber 93 may exhaust through a passage 94,'through the valve chamber 84, through a pipe 95 into the valve chamber 53 in the valve 35 and exhaust through the pipe 54 into the reservoir 44. It will be readily apparent from the foregoing disclosure that the feed control valve 35 is arranged to control the admission to and exhaust of fluid from the rapid gesed cylinder 33 and the grinding feed cylinder It is desirable to control the grinding feed of the wheel so that a grinding feed may be obtained during the initial grinding after which the feed may be slowed down to a finishing feed before the infeeding movement of the grinding wheel 13 is positively stopped. This is preferably accomplished by means of a finish feed control valve 91 and a grinding feedcontrol' valve 98 which 5 are arranged to control the exhaust of fluid from the cylinder chamber 92. A ball check valve 96 is provided in the pipe 90 so as to allow pressure to flow substantially unrestricted from the valve 35 through the pipe 90 to the cylinder 15. When fluid is exhausted from the cylinder chamber 92 when the piston 16 starts its movement to the right to cause a feeding movement of the grinding wheel It, the ball check valve 96 is arranged to prevent exhaust fluid passing therethrough so that the entire exhaust fluid from the cylinder chamber 92 must pass through either the grinding feed valve 90 or the finishing feed valve 91 or through both of the feed valves. During the initial infeeding movement of the grinding wheels as caused by the piston 16 fluid exhausted from the cylinder chamber 92 may pass through both of the valves 98 and 91. This exhaust of fluid serves to control the rate of the grinding feed.

In order to change the infeed from a grinding feed to a finishing feed, a solenoid valve I is provided comprising a valve stem IOI having valve pistons I02 and I03 formed integrally therewith, the valve pistons I02 and I03 being arranged to form a valve chamber I04. A compression spring I serves normally to hold the valve stem IOI in a right-hand end position (Fig. 1) so that fluid may exhaust through both of the valves 98 and 91. A solenoid I06 is provided which when energized serves to shift the valve stem IOI toward the left against the compression of the spring I05 so as to render the grinding feed control valve 98 inoperative. After the valve I00 has been shifted into a left-hand end position all fluid exhausting from the cylinder chamber 92 must exhaust through the finish feed control valve 91 which is adjusted to produce a slow finishing feed of the grinding wheel before the infeeding movement is finally stopped.

A stop abutment mechanism is provided for positively stopping the rotary motion of the feed screw I5 thereby limiting the infeeding movement of the grinding wheel I3. This mechanism may comprise a micrometer adjusting mechanism III carried by the feed wheel I9 which is arranged to adjustably support a stop abutment III. A stop pawl H2 is pivotally supported by a stud II 3 fixedly mounted on the front of the machine base. It will be readily apparent that when the stop abutment rotates in a counterclockwise direction with the feed wheel I9, the rotary motion of the feed screw I5 will continue until the stop abutment III engages a stop surface I M on the upper end of the pawl I I2.

It is desirable to feed the grinding wheel I3 first at a normal grinding rate and then to automatically reduce the feed to a very slow finishing feed before the rotation of the feed screw I5 is stopped by the mechanism above described. An arm I I1 is supported on the stud I I3 and is fixed- 1y connected to move with the stop pawl I I2. The stop pawl H2 is provided with an adjustable detent H6 which is arranged to be engaged by a cam II5 located adjacent to the stop abutment III. The detent H6 is preferably adjusted so that the cam II5 will engage the detent H6 and rock the stop pawl I I2 in a counter-clockwise direction before the stop surface I I4 is engaged by the stop abutment III. The rocking movement of the stop pawl II2 serves to impart a corresponding motion to the arm H1. The arm II1 supports an adjustable detent II8 which is arranged to engage an actuated roller I I9 of a limit switch I20. The limit switch I is preferably a normally open limit switch which is connected so'that when it is closed, the solenoid I06 is energized to shift the valve stem IOI toward the left thereby rendering the grinding feed control valve 98 inoperative during the finish grinding operation. It will be readily apparent from the foregoing disclosure that when the feed wheel I9 is rotated either manually or by movement of the piston 16, the rotary motion of the feed screw I5 and feed wheel I9 will move at a grinding feed rate until the cam II5 engages the detent H6 and rocks the stop pawl II2, the arm II1, the detent H8 in a counter-clockwise direction to actuate and close the limit switch I20 thereby energizing the solenoid I06, close the valve I00 thus rendering the grinding feed control valve inoperative so that thereafter fluid exhausting from the cylinder chamber 92 must pass through the finishing feed control valve 91. The slow finish feed continues until the stop abutment I I I engages the stop surface H4 on the stop pawl II2. In the preferred operation the grinding wheel remains in grinding contact with the work after the infeeding movement is stopped to permit the grinding wheel I3 to spark-out or finish grind the workpiece.

An automatic control mechanism is provided for automatically controlling the duration of the grinding cycle comprising an electric timer which is preferably an automatic re-set type adjustable timer such as for example the Microflex timer manufactured by the Signal Electric Corporation of Moline, Illinois. A feed cycle control lever I26 is pivotally supported by a stud I21 on the front of the lever base. The lever I26 is arranged to actuate a start switch I28 and a stop switch I29. When it is desired to start a grinding cycle, the lever I26 is rocked in a counter-clockwise direction to close the start switch I28 which serves to start the timer E25 and at the same time to energize the solenoid il to shift the feed control valve 39 so as to admit fluid under pressure to the cylinder chamber 5| to cause a rapid approaching movement of the piston 32, the wheel slide I I, and the grinding wheel I3. At the same time, the feed control valve 35 passes fluid under pressure to the cylinder chamber 93 to start movement of the piston 1i; toward the right (Fig. 1) to start a rotary motion of the feed screw. The rotary motion of the feed screw continues at a grinding feed rate as governed by the setting of the grinding feed valve 98 and the finish feed valve 91 until the cam H5 engages the detent IIG and closes the limit switch i220 thereby energizing the solenoid I06 to close the valve I00. After the valve I00 closes the grinding feed is automatically reduced to a finishing feed as governed by the finish feed control valve 91. The finish feed continues until the stop abutment III engages the stop surface I19 to positively stop the rotation of the feed screw I5 thereby limiting the infeeding movement of the grinding wheel I3. The grinding wheel it remains in operative grinding engagement with the workpiece being ground for a sparking-out period as governed by the electric timer I25. After a predetermined time interval has elapsed from the start of the grinding cycle, the timer I25 times-out thereby deenergizing the solenoid Al to release the compression of the spring 30 which returns the valve I35 to the position as illustrated in Fig. 1. This movement of the valve 35 serves to admit fluid under pressure to the cylinder chamber 50 to cause a rapid movement of the piston 32, the wheel slide I I and the grinding wheel I3 to an in- ;operative position. At the sametime fluid under 7. pressure is passed meme-cylinder chamber "92' to move the piston 15' toward theleft to rotate the feed wheel It and feed screw I in the reverse direction to return the parts to their initial posi tion.

It is desirable to provide a suitable clutch mechanism whereby the ieed'wheel may, if de-' sired, be operated independent of the cylinder 15 for setting up the machine, or for manual operation thereof Whendesired. The gear 18 is supported by anti-friction bearings I35 and- I36 (Fig. 3). The shaft 19 is provided With'an'in ternalgear I37 which is arranged to mesh with an external gear I39 which is'flkedly mounted to rotate with the gear 18. As shown in Fi'g." 3, the" gears I3"! and 38" are in mesh so that rotation of the gear 18 caused by the piston'lfi will impart a rotary motion to the feed screw I5. Whenit is desired to declutch the power mechanism from the manual control, the shaft I9 isinov'ed axially toward the right (Fig; 3) toslide the internal I37 out of mesh with the external gear 138, after which the feed wheel Hin-ay be rotated manually independent of the fluid pressure piston- 16.

To facilitate operation of the clutch mechanism above described, a manually operable clutch lever we having a hub portion Itl is arranged to rotate concentric with the axis of thefeed wheel Hi.- "ihe clutch lever I48 is provided with a downwardly extending arm hi2 having a stud I43 projecting downwardly from its lower end. The stud Ht-is arranged between a pair of a'd'justably' mounted oppos'edactuating screws" I44 and I45 which ar adjustably mounted on a yoked member I 35. The yoked member IMS is pivotally mounted on a stud It? carried by a bracket I48 which is fixedlymounted on the front of the machine base. The-yoked member I49 is provided with a downwardly extending yoked portion M9 which is provided with opposed studs I55 which ride withina groove i552 formed in an enlarged end portion of the sh'ait'lllp It will be readily apparent from the foregoing disclosure that when the clutch lever ido is rocked in a clockwise direction (Fig.1); the yoked member ME -I49 will b'e'rocked in'a counter-clockwise direction (Fig. 8) to slide the shaft 19" toward the right thereby moving the internal gear It; toward the right out of mesh with the external gear I382 A suitable detent mechanism is provided for holding the clu tclrpa'rt's either engaged-or disengaged. This mechanism may comprise an arrow ointed surface i5! formed on the lower end of the stud Hi3 (Fig.4). The arrow-pointed sur-' face i-Ei isarranged to engage a spring pressed arrow-pointcd plunger I52 which serves to hold the stud Mt either in a clutched or declutohd position.

The operation of the improved wheel feedin mechanism will be readily apparent from the foregoing disclosure. Assuming all of the valves to have been previously adjusted and a workpiece mounted in position for a grinding operation. The cycle control lever I26 is rocked in a counterclockwise direction to close the start switch I28. The closing of thestart switch I 28 serves tce'ner: gize the timer and thereby to energize the solenoid l-lto shi'it' the feed control valve 35 toward the right to energize an infeeding cycle. Fluid under pressure is passed from the valve 35 to the cylinder chamber 55' to cause a rapid ap preaching movement of the wheel slide II and gri ing wheel F3 which continues until the port 6$" 1sclosed aflier-whichtlre rapid approaching 8. v movement is slowed dd'v'v'n as eentroueaty the throttle Valve 7| just before the stop member 25 engages the stop screw 26. At the same time fluid is admitted to the Cylinder chamber 5| 0f the cylinder 33, fluid under "pressure is also passed into the cylinder chamber '33 to move the piston I6 toward the right thereby startinga controlled rotaryinotion of the feed screw I5 as governed by the grinding feed control valve 98 andthe finieh feed control valve 9?. The wheel slide continues to move at a grinding feed until the cam I I5 engages the detent I I6 and rocks the stop pawl I I2 so as to close the li'r'nit switch [20, as above desc'ribed' The closing of the-limit switch I20 e'ner gizes the'solenoid I06 to c'lo'se th e valve I00 thereby'rend'e'ring the grinding feed control valve 98 inoperative so that thereafter fluid exhausting fromthe cylinder chamber 92 must ekhaust' through the finish feed control valve 97 which reduces the grinding feed to a slower finishing feed shortly before the stop abutment I iI' engages the stop surface H4 on the pawl Hi! to positively lirnit' the-'infeeding movement of the grinding wheel. The grinding wheel'I remains in'grinding contact with the Work for a predetermined time interval as governed by the timer I25; When the timer l2i tinies out, the solenoid' il is deenergit'ed to admitfluid to the cylinder Chamber 50 to causea rapid rearward movement of tlie piston 32 together with the slide I I and grinding wheel I3 to move the Wheel It to an inoperative position; At the same time fiuid'under pressure is admitted through the cheek valveiie into the cylinder chamber-e2 to cause the piston I5 to move toward the left thereby rotating the feed screw in the reverse direction to te-set the feed mechanismgfor the next cycle of operation. As soon as the feed wheel I 9 starts rotation in a clockwise direction, during the rte-setting motion, the cam I I5 moves out 'ofengagerhent with the deterit IIG thereby allowing'the' limit switch I20 to open to deenergige the: solenoid I65 thereby opening the valve N30 for the next grinding cycle. This" cycle of operation may then 'be successively repeated by merely actuating the cycle control lever Hi).

If desired, the electric tiiner [25' may be connected so that it is energized by the closing of the limit switch I25 at the same time the Slow feed is initiated to set the tirher in motion se that after a predetermined time interval, the timer I25 will operate to cleener'giz'e the solenoid M thereby completing the grinding cycle. In this latter a1"- rangement, thetim'er I2 5 instead of controlling the over-all grinding cycle would control the slow down or finish grinding operation and the time interval in which the grinding wheel is held stationary'.

will thus be seen that there has" been provided by this inventiorr'apnafatus infivhich the various obj-cots hereinabove set'forth together witlimany-thoroughly practical advantages are successfully achieved. As many possible embodimerits may he made of the above invention and as' many changes mightbe made in the embodiment above set forth, it is to be understood that all matter heremtefore set fo'rth 'or sh'owr'r' in the accom panying' drawings is to be interpreted as illustrative and not in a limiting sense.

I claim: 7

1 In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel thibil, a feeding mechanism to-fe'ed said slide, a rotatable feed- Wheel "therefor; an adjustable step-abutment oir sa'id i'e'ed wheel-,-'a inovably wheel for moving said pawl after a predetermined grinding feed and before the stop abutment engages said pawl to actuate said limit switch so as to reduce the infeed to a predetermined finishin feed.

2. In a grinding machine, as claimed in claim 1, in combination with the parts and features therein specified of a cam on said wheel, and an ad" justable detent on said stop pawl which is engaged by said cam to move the pawl so as to actuate said limit switch thereby reducing the grinding feed to a finishing feed.

3. In a grinding machine, as claimed in claim 1, in combination with the parts and features therein specified of a cam on said'feed wheel, an adjustable detent on said pawl which is engaged by said cam so as to move said pawl, a second detent on said stop pawl to engage and actuate said limit switch thereby reducing the grinding feed to a finishing feed.

4. In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel thereon, means to move said slide rapidly to and from an operative position, a feeding mechanism to feed said slide, a rotatable feed wheel therefor, an adjustable stop abutment on said feed wheel, a pivotally mounted stop pawl positively to l1m1t rotation of the feed wheel in one direction, power operated means continuously to actuate said feeding mechanism to cause a continuous speedin movement of the grinding wheel, means to control said power means to produce a grinding feed, means to control said power means to produce a finishing feed, means including a limit switch to render said grinding feed control inoperative, and means on said feed wheel to rock said pawl before the stop abutment engages said pawl after a predetermined grinding feed to actuate said limit switch so as to reduce the feed to a predetermined finishing feed.

5. In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel thereon, a feed mechanism to feed said slide, a feed wheel therefor, an adjustable stop abutment on said feed wheel, a pivotally mounted stop pawl positively to limit rotation of the feed wheel, means including a fiuid motor continuously to actuate said feed mechanism to cause a continuous feeding movement of the grinding wheel, an adjustable throttle valve to control th exhaust of fluid from the motor so as to produce a grinding feed, a second adjustable throttle valve to control the exhaust of fluid from the motor so as to produce a finishing feed, means including a limit switch to render the first adjustable throttle valve in operative, and means including a cam on said feed wheel to rock said pawl after a predetermined grinding feed and before the stop abutment engages said pawl to actuate said limit switch so as to reduce the feed to a predetermined finishing feed.

6. In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel thereon, means including a fluid motor to move said slide rapidly to and from an operative position, a feed mechanism to feed said slide, a feed -10. wheel therefore, an adjustable stop abutment on said feed wheel, a pivotally mounted stop pawl positively to limit rotation of the feed wheel, means including a fluid motor continuously to actuate said feed mechanism to cause a continuous feeding movement of the grinding wheel, an adjustable throttle valve to control the exhaust of fluid from the second motor so as to produce a grinding feed, a second adjustable throttle valve to control the exhaust of fluid from the second motor so as to produce a finishing feed, a solenoid-actuated valve to render the first throttle valve inoperative, means including a limit switch to actuate said solenoid valve, and a cam on said wheel to rock said pawl after a predetermined grinding feed and before the stop abutment engages said pawl so as to actuate said limit switch and solenoid-actuated valve to reduce the feed to a predetermined finishing feed.

'7. In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel thereon, means including a fluid motor to move said slide rapidly to and from an operative position, a nut and screw feed mechanism to feed said slide, a manually operable feed wheel therefor, an adjustable stop abutment on said feed wheel, a pivotally mounted stop pawl to limit the rotation of the feed wheel and feed screw, means including a fluid motor continuously to rotate said feed screw to cause continuous feeding movement of the grinding wheel, an adjustable throttle Valve to control th exhaust of fluid from the motor so as to produce a grinding feed, a second adjustable throttle valve to control the exhaust of fluid from the second motor so as to produce a finishing feed, a solenoidactuated valve to render the first throttle valve inoperative, means including a limit switch operatively connected to actuate the solenoidactuated valve, and a cam on said stop abutment to actuate said pawl after a predetermined grinding feed and before the stop abutment engages said pawl so as to actuate said limit switch and solenoid-actuated valve to reduce the feed to a predetermined finishing feed.

8. In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel thereon, means including a fluid motor to move said slide rapidly to and from an operative position, a solenoid-actuated control valve therefor, an electric timer to control the grinding cycle, means including a cycle start switch to energize said timer and said control valve to initiate a feeding cycle, a nut and screw feed mechanism to feed said slide, a manually operable feed wheel therefor, an adjustable stop abutment on said feed wheel, a pivotally mounted stop pawl to limit the rotation of the feed wheel and feed screw, means including a fluid motor to rotate said feed screw, an adjustable throttle valve to control the exhaust of fluid from the second motor so as to produce a grinding feed, a second throttle valve to control the exhaust of fluid from the second motor so as to produce a finishing feed, a solenoid-actuated valve to render th first throttle valve inoperative, and a limit switch actuated by said pawl before the stop abutment engages said pawl so as to actuate said second solenoid-actuated valve to reduce the feed to a predetermined finishing feed, said timer serving after a predetermined time interval to cause a rearward movement of the grinding wheel to an inoperative position.

9. In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel thereon, means, including a piston. and'cylinder to move said slide to and from an operative position, a nut and screw mechanism to feed said slide, a rotatable feed Wheel therefor, an adjustable stop abutment on said feed wheel, a

pivotally mounted stop pawl positively .to limit' stop abutment engages ,saidpawl so as to actuate the solenoid-actuated valve to reduce the feed to a predetermined finishing feed.

10. In a grinding machine having a transversely movable wheel slide, a rotatable grinding wheel therein, means including a piston and cylinder to move said slide to and from an operative position, a solenoid-actuated control valve therefor, an electric timer to control the over-all grinding cycle, means including a cycle start switch to energize said timer and said control valve to initiate a feeding cycle, a nut and screw mechanism to feed said slide, a rotatable feed wheel therefor, an adjustable stop abutment on said feed wheel, a pivotally mounted stop pawl positively to limit rotation of the feed wheel and 7 said screw, means including a piston and cylinder to rotate said feed screw, a solenoid-actuated control valv 'to control the admission to and exhaust of fluid from both of said cylinders, an

adjustable throttle valve to control the exhaust of fluid from the second cylinder so as to produce a grinding feed, a second adjustable valve to control the exhaust of fluid from the second cylinder so asto produce a finishing feed, a solenoid-actuated valve to render said first throttle valve inoperative, and a limit switch actuated. by said pawl before the stop abutment engages said pawl so as to actuate the solenoid-actuated valve to reduce the feed to a predetermined finishing feed, said timer serving after a predetermined time interval to deenergize said solenoid-actuated control valve to cause both of the pistons to return to initial positions thereby moving the grinding wheel rearwardly to an inoperative position.

- HOMER, L. SWAINEY.

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